Pivotal roles for cancer cell–intrinsic mPGES-1 and autocrine EP4 signaling in suppressing antitumor immunity
Nune Markosyan, Il-Kyu Kim, Charu Arora, Liz Quinones-Ware, Nikhil Joshi, Noah Cheng, Emma Y. Schechter, John W. Tobias, Joseph E. Hochberg, Emily Corse, Kang Liu, Varenka Rodriguez DiBlasi, Li-Chuan (Eric) Chan, Emer M. Smyth, Garret A. FitzGerald, Ben Z. Stanger, Robert H. Vonderheide
Nune Markosyan, Il-Kyu Kim, Charu Arora, Liz Quinones-Ware, Nikhil Joshi, Noah Cheng, Emma Y. Schechter, John W. Tobias, Joseph E. Hochberg, Emily Corse, Kang Liu, Varenka Rodriguez DiBlasi, Li-Chuan (Eric) Chan, Emer M. Smyth, Garret A. FitzGerald, Ben Z. Stanger, Robert H. Vonderheide
View: Text | PDF
Research Article Immunology Oncology

Pivotal roles for cancer cell–intrinsic mPGES-1 and autocrine EP4 signaling in suppressing antitumor immunity

Abstract

Tumor cell–derived prostaglandin E2 (PGE2) is a tumor cell–intrinsic factor that supports immunosuppression in the tumor microenvironment (TME) by acting on the immune cells, but the impact of PGE2 signaling in tumor cells on the immunosuppressive TME is unclear. We demonstrate that deleting the PGE2 synthesis enzyme or disrupting autocrine PGE2 signaling through EP4 receptors on tumor cells reverses the T cell–low, myeloid cell–rich TME, activates T cells, and suppresses tumor growth. Knockout (KO) of Ptges (the gene encoding the PGE2 synthesis enzyme mPGES-1) or the EP4 receptor gene (Ptger4) in KPCY (KrasG12D P53R172H Yfp CrePdx) pancreatic tumor cells abolished growth of implanted tumors in a T cell–dependent manner. Blockade of the EP4 receptor in combination with immunotherapy, but not immunotherapy alone, induced complete tumor regressions and immunological memory. Mechanistically, Ptges- and Ptger4-KO tumor cells exhibited altered T and myeloid cell attractant chemokines, became more susceptible to TNF-α–induced killing, and exhibited reduced adenosine synthesis. In hosts treated with an adenosine deaminase inhibitor, Ptger4-KO tumor cells accumulated adenosine and gave rise to tumors. These studies reveal an unexpected finding — a nonredundant role for the autocrine mPGES-1/PGE2/EP4 signaling axis in pancreatic cancer cells, further nominating mPGES-1 inhibition and EP4 blockade as immune-sensitizing therapy in cancer.

Authors

Nune Markosyan, Il-Kyu Kim, Charu Arora, Liz Quinones-Ware, Nikhil Joshi, Noah Cheng, Emma Y. Schechter, John W. Tobias, Joseph E. Hochberg, Emily Corse, Kang Liu, Varenka Rodriguez DiBlasi, Li-Chuan (Eric) Chan, Emer M. Smyth, Garret A. FitzGerald, Ben Z. Stanger, Robert H. Vonderheide

×

Figure 2

Ptger4 KO in T cell–low tumor cell line abolishes implanted tumor growth in a T cell–dependent manner.

Options: View larger image (or click on image) Download as PowerPoint
Ptger4 KO in T cell–low tumor cell line abolishes implanted tumor growt...
(A) Ptger4 mRNA expression by Q-PCR in control EV and TL 6419c5 Ptger4-KO clonal tumor cell lines (n = 3). (B) S.c. implanted non-transduced 6419c5 (parental), EV, and Ptger4-KO tumor growth (n = 6, 1 of 3 experiments with similar results shown). (C) Individual tumor growth curves of tumors in B. The black vertical arrow indicates the rechallenge of tumor-free mice with control cell implants on day 85 (n = 11: 5 and 6 mice cured of Ptger4-KO E10 and Ptger4-KO C3 tumors, respectively). (D) Control and Ptger4-KO tumor growth in WT and Ptger4-KO hosts (n = 10, 1 of 2 experiments with similar results shown). (E) Flow cytometric analysis of T cells in control and Ptger4-KO s.c. tumors 11 days after implantation (n = 10, 1 of 3 experiments with similar results shown). (F) Flow cytometric analysis of myeloid cells in control and Ptger4-KO s.c. tumors, 11 days after implantation (n = 10, 1 of 3 experiments with similar results shown). (G) Flow cytometric analysis of s.c. tumor-draining lymph nodes 10 days after implantation (n = 9–10, 1 of 3 experiments with similar results shown). (H) S.c. implanted control and Ptger4-KO tumor growth with and without CD4+ and CD8+ T cell depletion (n = 10). (I) Rechallenge control tumor growth with and without CD4+ and CD8+ T cell depletion in hosts after complete regression of Ptger4-KO s.c. implants (n = 10). (J) Ptger4 mRNA expression by Q-PCR in control E0771 EVb3 and E0771 OEb8 mammary clonal tumor cell lines (n = 3). (K) Growth curves of orthotopically implanted E0771 EVb3 and E0771 OEb8 mammary tumor cell lines (n = 4–5). Data are presented as median (A, E, and F), mean ± SEM (B, D, and H–J), and in C, each line represents an individual tumor. Significance was assessed by ordinary 1-way ANOVA with Tukey’s multiple-comparison test (A), 2-way ANOVA with Tukey’s multiple-comparison test for main-effects analysis (B, D, H, I, and K), or 2-tailed unpaired Student’s t test (E–G and J). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.